1. Field of the Invention
The disclosure relates to the field of air-moving systems. More specifically, the disclosure relates to air-moving systems having replaceable filters, such as vacuum cleaners and air-filtration devices.
2. Description of the Related Art
Vacuum cleaners are notoriously dusty and dirty, requiring some method to separate the dust and the dirt from air that is exhausted back into the surroundings. Hence, filters are commonly used to perform this separation function. There often is a need to remove and re-attach the filter, for example, when cleaning the filter or replacing it with a new filter. With the type of vacuum cleaners known as “wet/dry” vacuum cleaners, the filter is often also removed when the vacuum cleaner is suctioning liquids. Thus, special structures accompany a typical wet/dry vacuum cleaner to accommodate removing and replacing the filter.
Typically, a suction system with a motor creates the vacuum and is mounted in a lid that is removably attached to a collection drum for receiving the vacuumed materials. A portion of the lid, herein termed a mounting assembly, extends at least partially downward into the drum and mounts a filter support assembly, such as commonly known as a “cage,” that generally covers a vacuum intake to the suction assembly in the lid. The cage can be made of plastic such as polypropylene, is generally a cylindrically-shaped molded part having a series of axial and circumferential ribs with a large percentage of open surface area to support the filter extended around the cage, and prevents radially inward collapse of the filter during operation. The axial ribs align with a longitudinal axis through the cage and the circumferential ribs are generally at rights angles to the axial ribs. The cage construction creates a relatively stiff component in the axial direction. In addition to supporting the filter, the cage provides a safety shield from access to the impeller, and contains a float that protects the vacuum cleaner from water being inadvertently suctioned into the impeller.
The vacuum system inside the lid suctions external dirty air or water through a hose into an opening in the drum or lid so that the dirt or water is deposited into the drum. Remaining material, mainly air, then flows radially inward through the filter for removal of dirt and debris and continues through the cage into a suction impeller in the lid, and then is exhausted from the vacuum cleaner.
The filter is commonly attached to the mounting assembly by a threaded stud on the end of the cage and places the filter in axial compression, utilizing the longitudinal stiffness of the axial ribs. The filter is inserted over the cage, and a mounting flange of rigid material, such as plastic, is attached to the cage or mounting assembly and used to compress or “sandwich” the filter between the flange and the mounting assembly. The compressive force on the entire filter body and its filter element is the primary force used to seal the filter to the vacuum cleaner and prevent unwanted leakage through the vacuum cleaner. Thus, a structurally sound and supportive cage is important to the overall function of the filter and in general the vacuum cleaner. The filter may also be attached in position by some other method, such as clamping one or more seals of the filter directly to the mounting assembly or lid. A structurally rigid cage is again necessary to guard against entry of unwanted objects, or fingers, into the impeller and to house the intake cutoff float.
Experience has shown that the cage can become damaged in handling and operation in part due to the significant stiffness caused by the axial ribs. The damaged cage may not support the intended axial forces on the cage, the filter or both.
Therefore, there remains a need for an improved cage design and system for such a vacuum cleaner and other air-moving systems.